This invention relates to an improved ridged wave-guide antenna.
The two-way radio user in an urban environment is plagued today by the problem of vandalism of car radio antennas and, what is worse, burglary or radio equipment. In most cases, the visibly mounted non-broadcast antenna triggers the pilferage of the radio control head and even the removal of the transceiver from the trunk. Nothing could be more serious for an undercover officer or other two-way radio user than to leave his car and return to find a broken antenna or, worse, that his radio has been stolen.
What the two-way communications community therefore requires is an efficient and easily constructed covert antenna. Varieties of disguised antennas have been used by law-enforcement agencies since the advent of mobile radio. Such antennas have been disguised as AM broadcast antennas mounted on automobile fenders, as side-view mirrors and in other more exotic configurations. Some agencies have cut a large hole into the car's roof or trunk lid to form a half-wave slot antenna, which was then covered with fiberglass and refinished to blend with the rest of the car body. Military studies have been performed on the feasibility of insulating the engine hood or trunk lid from the rest of the body to form a resonant slot antenna.
None of these solutions have proved completely satisfactory. AM broadcast and side-view mirror antennas are still subject to vandalism, and both have very distorted radiation patterns. Side-view mirror antennas have been found to be extremely inefficient. Furthermore, the trunk lid, hood or roof slot antennas are impractical since they are far too expensive to fabricate and can never be transferred from one vehicle to another.
It is, therefore, an object of the present invention to provide an antenna that is completely covert and impossible to detect or vandalize.
It is another object of the present invention to provide such an antenna, the installation of which is quick and easy and can be accomplished without altering a vehicle in which it is to be installed.
A further object and feature of the present invention resides in the novel details of construction which provide a covert antenna that is relatively low in cost and which may be readily manufactured, utilizing well-known techniques.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed for the purposes of illustration only and not as a definition of the limits of the invention for which reference should be made to the appending claims.